1. Field of the Invention
The present invention pertains to pipe connector apparatus and methods of installation. Specifically, it pertains to apparatus and installation methods for connecting pipes or conduits in particularly difficult environments, e.g. subsea environments.
2. Description of the Prior Art
It is known to connect pipes using tapered slip wedges and correspondingly tapered slip bowls for forcing the slip wedges from a radially expanded position, in which a pipe member may be received therein, to a radially contracted position in which the slips grip the exterior of the pipe firmly clamping or wedging the pipe in a fixed position. In prior art connectors, the slips are moved to the gripping or clamped position by relative movement of the slip bowl and slips. Such movement is generally effected by application of fluid under pressure to an annular piston or a plurality of piston rams arranged around the axis of the pipe connector. Examples of such prior art apparatus may be seen in U.S. Pat. Nos. 3,393,926; 3,704,033 and 3,986,728.
In subaquatic environments, hydraulic pipe connectors have the advantage of requiring only that a diver connect the source of hydraulic pressure to a pressure port on the connector to enable slip wedges to be forced into an engaged position to clamp the connector against the pipe. However, such arrangements have a disadvantage in that when the hydraulic pressure source is later disconnected from the pipe connector, there are problems of sealing against escape of hydraulic fluid in order to prevent disengagement of the slips. Furthermore, such connectors are relatively expensive and with continuing development in underwater welding, may not remain competitive for many years.
To eliminate the problems associated with hydraulic actuation, connectors have been developed for actuation by non-return mechanical means. In U.S. Pat. No. 3,999,782, a connector is disclosed in which the slips are driven apart by a screw arrangement, comprising thrust sleeves threadedly engageable with a common drive sleeve. The drive sleeve may be driven by a worm wheel arrangement so that as the worm is rotated, the worm wheel rotates the drive sleeve to drive the thrust sleeves and slips away from the worm wheel by virtue of opposed hand threaded interengagement between the thrust sleeve and the drive sleeve. Another but more simple mechanically actuated connector is described and claimed in co-pending United States Patent Application Ser. No. 788,159.
Even though recently developed mechanical connectors have eliminated some of the problems associated with hydraulic connectors, they do not provide the ultimate answer in all connector applications. Furthermore, while they may be less expensive to install and maintain than hydraulic connectors, they are still relatively expensive and may not long compete with improved underwater welding processes. Furthermore, while some pipe connectors of the prior art provide means for further tightening of the annular seals associated therewith, such means could be improved in reliability and effectiveness.